1. Field of the Invention
The present invention relates to a method and apparatus for converting an image captured by a camera into a digital signal, then transmitting the converted digital signal via a network, such as a code division multiple access (CDMA) network, for display on screens of portable wireless terminals such as cell phones or PDA's. The present invention also enables users to monitor the image captured by a camera through a wireless device from a remote place.
2. Description of the Related Art
As is generally known in the art, in sending a message through a conventional mobile communication system, a short message is entered into a mobile communication terminal or a web site, and the message is then transmitted to a messaging server providing a mobile communication service. The transmitted message is stored in a message storage space of a receiver, and if the fact that the message has arrived is notified to the receiver through a mobile communication network, the receiver enables a call path to be set between the messaging server and the receiver's wireless terminal. Accordingly, the receiver can receive the short message. Further, a motion picture may be sent or received through a system capable of supporting a messaging service. The performance and screen display functions of wireless terminals such as cell phones and PDAs have been improved. Also, wireless terminals have been utilized for various purposes. Additionally, since images may be converted, compressed and transmitted in a remote digital image method by means of cell phones or PDAs, users can monitor an image captured by a camera installed in a remote place, by means of the wireless terminals.
A conventional messaging service system is shown in FIG. 1. The messaging service system includes a sender's computer 10, a messaging system 20, a mobile communication terminal 30, conventional mobile communication equipment and web servers 60, 70. The messaging center web server 60 includes web servers for managing web sites providing motion picture messaging service through the Internet. The sender's computer 10 connects with the messaging center web server 60 through a web browser 11, and may go through steps such as member registration and authentication, and so on. In this case, by means of an implied or expressed method, users receive a URL directing them to receive a plug-in such as Active-X of the Microsoft Co., Ltd or Java through the web server 60, which are programs that enable the motion picture messaging service, and the users download the plug-in and install it on the computer. As is known in the art, such plug-ins may exist in many locations on the Internet, and the plug-in is shown as a plug-in web server 70 included in the messaging system 20 in FIG. 1.
Also, the sender's computer 10 includes a microphone 17 for inputting a voice signal, a sound card or voice processing card 15, a camera 18 for inputting a motion picture and a camera interface 16 such as a USB port. A motion picture processing module 14 preferably performs a decimation process on color image data and also preferably reduces the resolution of the color image. Further, the motion picture processing module 14 preferably converts the color image data into a gray image with either two gradation values or four gradation values, then performs an additional signal compression processing. A voice processing module 13 receives voice data from a device driver of the sound card or voice processing card 15, and encodes the voice data with a compression algorithm which can be decoded with a voice codec selected for a general voice call of a mobile communication terminal. The motion picture and voice signals processed as described above are converted into motion picture message information, which is a data packet having a predetermined size, together with control information such as control data for a receiver's phone number and a lip sync, for reproducing the motion picture and voice signal. Then, the motion picture and voice signal is transmitted to a motion picture message server 21 through a plug-in control module.
The messaging system 20 includes a messaging server 22 called a SMS center and a gateway 23 called IWF (inter-working function). A mobile communication network 40 is a well-known system component or is very similar to existing messaging systems. The motion picture message server 21 stores a predetermined size of motion picture message information in memory spaces divided according to receivers. The motion picture message server 21 requests that a typical messaging server 22 notify an arrival of such a motion picture message to the mobile communication terminal 30 of a receiver. Further, the motion picture message server 21 transmits the motion picture message information through user identification, when the receiver, who receives such a requirement, sets a call path. The messaging server 22 may utilize the existing SMS. According to the SMS method, a user recognizes whether a message is arrived or not, through a beep, or other notification, and sets a call of a data mode between the motion picture message server 21 and the mobile communication terminal 30 by pressing an appropriate selection button. Next, the user selects a predetermined message from among a given list, and receives the information corresponding to the selected information from the motion picture message server 21.
The mobile communication terminal 30 includes a call circuit 31 including a voice demodulation module 32, a display 33, a display circuit 34 and a messaging service module 35, and is a well-known type of terminal or is one similar to such That is, when a message is received by means of the call circuit 31, the messaging service module 35 receives the message. Voice information from the received message is demodulated by means of the voice demodulation module 32, thereby enabling the demodulated voice information to be outputted to a speaker. Further, the messaging service module circuit 35 enables motion picture information from among the demodulated messages to be demodulated by means of a motion picture demodulation module 36. The demodulated motion picture information is written in the display memory of the display 33 by frame, through the display circuit 34, thereby enabling the motion picture information to be reproduced.
FIG. 2 is a flow chart illustrating a transmitting and receiving method of a motion picture message by means of the aforementioned construction. The sender's computer 10 is connected, by means of an operation by a user who would like to transit the motion picture message, to the messaging center web server 60 providing motion picture messaging service (step S51). The messaging center web server 60 may exist anywhere on the Internet, or may be provided by a plurality of service providers. The sender's computer 10 is connected to a plug-in web server 70 existing at a predetermined address on the Internet through an expressed or implied method, by means of commands encoded on a web page of the messaging center web server 60, so as to utilize a motion picture messaging service initially, and downloads a plug-in control module 12 such as Active-X control of the Microsoft Co., Ltd, which can support the motion picture messaging service (step S52). Then, the user enables a motion picture to be recorded through a camera 18 and a microphone 17 installed on the sender's computer 10 (step S53). The recorded motion picture is transmitted to the motion picture message server 21.
The motion picture message server 21 may physically be the same server as the messaging center web server 60 or a plurality of motion picture message servers 21 may exist. The motion picture message server 21 divides a memory space into a plurality of spaces according to receivers, and stores the message for a predetermined period such as one month (step S54). Then, the motion picture message server 21 requests that the messaging server 22, which provides a typical messaging service, notify an arrival of the message. The messaging server 22 notifies the fact that the message has arrived to a receiver through the mobile communication network 40, according to messaging protocols such as SMS, ISMS and WAP (step S55). However, since the mobile communication terminal 30 does not have sufficient memory, it receives shortened arrival notification information, rather than the entire motion picture message (step S56). Accordingly, in order to receive a entire message, the mobile communication terminal 30 is connected to the messaging server in a data communication mode through the mobile communication network (step S57), and then receives the motion picture message (step S58) and reproduces it frame by fame.
However, in transmitting the motion picture message information, the message may be transmitted by the entire message or by individual image frames. When the motion picture message information is transmitted by message, a selected entire message is downloaded while a communication channel is open. Also, the mobile communication terminal 30 stores the downloaded motion picture message information in a memory, and then obtains access to the memory, thereby reproducing the motion picture message information. Accordingly, this method is problematic in that sufficient memory space needs to be provided in the mobile communication terminal.
The method of transmitting the motion picture message information by image frames is applicable when the memory capacity of a mobile communication terminal is insufficient and a condition of a call path is relatively good. Within the limit of a bandwidth of a wireless communication, a server transmits a selected message by fame, and a reception side receives the selected message in real time and reproduces the received message. However, the transmission unit is restricted by the conditions of reproduction, such as the bandwidth of the wireless communication and the memory space of the terminal.
Further, comparing to a wire data transmission method, this wireless data transmission method has a strong likelihood of data loss, data transmutation and transmission errors occuring. Further, as the amount of data to be transmitted grows larger, the likelihood that such errors will occur becomes higher.